1. Field of the Invention
The present invention relates to a switch provided with an electronic element on a movable contact of a switch. Particularly, the invention relates to an improvement of a switch device having an electronic element, such as a diode, for preventing reverse flow of current on a contact portion to reduce the number of interconnections.
2. Description of the Related Art
Conventionally, there has been a switch device provided with several switches as in an automobile combination switch. This related art combination switch has a plurality of operation members comprising a lever, a rotary knob and a push button, and a multiplicity of contact members operating on the operation members, thus being complicated in switch-device structure. In the switch device, the increased contact members increases the number of terminals or harnesses connected to the contact members, increasing connection work and the number of parts and hence leading to the increase of cost.
There is, as a technology for eliminating such problems, a device of a combination switch disclosed, e.g., in Japanese Utility Model Preliminary Publication(KOKAI)No. 5-79843. This device is intended to simplify the structure of a combination switch and reduce cost by making the fixed contact of the switch to a common contact and controlling electronic signals of each switch by one electronic control circuit.
The device disclosed in the foregoing publication decreases conventional five into three of output contact terminals connecting from the turn and light switch to the electronic control circuit and conventional five into three of output contact terminals connecting from the wiper and washer switch to the electronic control circuit, thereby reducing the number of parts and assembling processes. However, there are a number of switch devices in the combination switch. Even if the foregoing common contacts are used, the number of terminals and harnesses to be reduced is limited, which number still remains many.
It can be considered to make the contact portions of an electric circuit as shown in FIG. 11 into a matrix as a means to further reduce the number of contact terminals in the related art. In FIG. 11, 68 is an electronic control circuit of a combination switch, 69 is a contact portion made in matrix of a turn and light switch and wiper and washer switch, and 70 are lead wires connecting between the contact portion 69 and the electronic control circuit 68. It is possible to further reduce the number of contact terminals by making a matrix in this manner.
However, in the combination switch that the related art contact portion 69 is made in a matrix, one lead wire can be utilized for signals exclusive for the lighting system and another for signals exclusive for the wiper system. It can be considered that such use leads to a functional failure for the lighting system (or the wiper system) entirety in the event of occurrence of trouble, such as disconnection, in the lead wire. The lead wires in plurality are preferably used commonly to the lighting system and the wiper system.
However, it can be considered that, where connection and disconnection of the switches are to be made by switching the contacts with the lead wires used commonly, unintended contacts are simultaneously put in a connection state due to the configuration of many switches. In the case of encountering such simultaneous connection, there is a problem that malfunction occurs in the electronic control circuit 68.
Therefore, in order to prevent malfunction due to current flow-in in the electric circuit of the electronic combination switch 71 as shown in FIG. 11, it can be considered to provide a diode 72 for preventing reverse flow of current in the electric circuit within the control circuit 74 between contacts and an IC 75 or within the combination switch 71.
The combination switch 71 is provided with a multiplicity of switch devices. In the case of the wiper switch 73, for example, knob manipulation moves one movable contact 73a providing switching from an OFF contact 73b to an INT contact 73c, LO contact 73d or HI contact 73e. In this example, it is necessary for one of the diodes 72 to be provided between each of the output portions of the OFF contact 73b, the INT contact 73c, the LO contact 73d and the HI contact 73e and the IC 75 of the control circuit 74, thus increasing the number of diodes used and increasing the cost of the combination switch 71.
Meanwhile, where the diodes are provided on a printed board or pole board of the wiper switch 73, the occupation space of the diodes increases, thus increasing the size of the printed board or pole board and hence the overall size of the combination switch. Where conversely the pole board is limited in size, another problem arises that the diodes occupy over the board surface making it impossible to secure a space for providing fixed contacts.
It is an object of the present invention to provide a switch device having electronic elements provided in proper positions and having a reduced number of switch terminals and harnesses.
The present invention has been made in order to eliminate the foregoing problems in the related art.
(1) A switch device according to the present invention comprises a plurality of fixed contacts and a plurality of movable contacts to contact the fixed contact, wherein the movable contacts each has an electronic element provided among contact members.
(2) In the switch device as set forth in (1), the electronic element comprises a diode.
(3) In the switch device as set forth in (1) or (2), the movable contacts each has the electronic element arranged in a connecting portion where the plurality of contact members join together.
(4) In the switch device as set forth in (3), the movable contacts each has a holding member fixing the electronic element and the connecting portion where the plurality of contact members join together.
(5) In the switch device as set forth in (4), the holding member forms a mover.
(6) In the switch device as set forth in (1), (2) or (3), the movable contact comprises two conductive metal rod-like members, and the two conductive metal rod-like members each forms a contact portion in one end and has the other end fixed on an end of each of the electronic elements.
(7) In the switch device as set forth in (1), (2), (3), (4), (5) or (6), the movable contacts each constitutes a contact member for an automobile combination switch.